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What Is The Longest Interstate Highway In The US?

Right and/or Left

Amanda and I just finished a 4 hour trip from Washington, DC to our hometown in Pennsylvania. As I sat in the car traveling on a long stretch of highway, I began to wonder what the longest Interstate Highway in the US was.

US Interstate Highway System

First, I find it important to point out that I am talking about Interstate Highways. Interstate Highways are all roads but roads are not all Interstate Highways. Got it?

The Interstate Highway System (also referred to the Dwight D. Eisenhower National System of Interstate and Defense Highways) is a network of highways, freeways, expressways, etc. that stretch across the entire US. It was authorized by the Federal Aid Highway Act of 1956 and apparently took 35 years (!) to complete all parts of the project. The cost has been estimated at $425 billion (in 2006 dollars). Pretty costly but well worth it if you ask me!

Interstate 90 (3,101.13 miles)

So, now that you know about the Interstate Highway System, it’s time to talk about the longest one.

Interstate 90 is the longest and stretches from Boston, MA to Seattle, WA for a total of 3,101.13 miles. From Boston to the Wisconsin-Illinois the majority of the highway is tolled.

Interstate 90 goes through the following major cities:

  • Boston, MA
  • Albany, NY
  • Buffalo, NY
  • Cleveland, OH
  • Chicago, IL
  • Sioux Falls, SD
  • Billings, MT
  • Spokane, WA
  • Seattle, WA

Have you ever traveled on Interstate 90?



Additional Reading:


Interstate Guide


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